Alternating-current meter.



10.870,970. PATENTEDNOV. 12, 1907. R. o. LANPHIER.

ALTBRNATING CURRENT METER.4

APPLIoATIoN FILED snrjr. 5.1904.

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1HE Nmzms PETER: co., wAsmNcwN, n. c.y

UNITED STATES PATENTv OFFICE.

ROBERT C. LANPHIER, OF SPRINGFIELD, ILLINOIS.

AIiTERNATING-CURRENT METER.

Specification of Letters Patent.

Patented Nov. 12, 1907.

Application filed September 8 1904- Serial No. 223,693.

pertains to make and use the same, reference being had to the accompanying drawings, 'which form a part of this specification.

My invention relates in general to meters for measuring electric currents, and more particularly to meters for measuring alternating currents.

It has heretofore been common to employ motor wattmeters of the well-known mercury type for measuring Adirect currents, but so far as I am aware no-successful attempt has been made prior to my invention to employ such type of meter for measuring alternating currents. This type of meter, asis well known'in the art, consists of a rotatable conductdr for the load current immersed in mercury and located in inductive relation to a. magnetic field, the reaction of which upon the current rotates the conductor of the load current. An embodiment of this type of meter is covered by United States Patent No. 738,902, granted to Guttman and myself September l5, 1903, which consists of a copper disk immersed in a body of mercury and exposed to a strong magnetic field, the arrangement being such that the main current traverses the-disk diametrically while a shunt current passes through the' energizing pressure coils of the magnetic field thereby rotating the disk.

The principal diiculty encountered in using a meter of the type referred to for measuring alternating currents is that the current in the shunt coils, due to their great self induction, will lag so much that the field produced by such coils will have a difference of phase 'from the impressed E. M. F. oi 70 degrees or more.

This difference of phase results in the meter having almost no torque when the load is non-inductive and in having on inductive load a torque which willgreatly increase as the power factor of the Aload decreases and the main load current thereby comes more nearly in phase with the lagging magnetic eld'.

Another difficulty which arises, when the first difficulty above mentioned has been overcome, in the use of a meter ofthe type referred to for alternatingl currents is that the speedv of rotation of the disk does not increase proportionately with the increase in load. When a meter of this type is used' for measuring direct currents there is quite a large error on full load, the meter running from 20 to 25 75 slow if no compensation is provided. The error when the meter is used for alternating currents is, however, more than twice as great as or direct currents, being nearly 70 72 difference between the speed on one ampere and the speed on ten amperes when'no compensationl is provided.

The primary object of my invention is to provide a mercury motor watt-meter for measuring alternating currents which will be free from the objections above enumerated.

A further object of my invention is to provide a mercury motor watt-meter of the type above mentioned for alternating currents in which an electro-motive force will be impressed on the shunt coils so as to bring the magnetic' field produced by them in phase with the line pressure, that is to say, with the load current on nonindu'ctive load, which will render the meter capable of measuring an inductive or non-inductive load with equal accuracy.

A further object of my invention is to provide a mercury. motor watt-meter of the type described for measuring alternating currents inwhich a portion of the main current will be shunted around the rotary conductor, more of the current being proportionately shunted on light load than on full load, whereby the speed of rotation of the disk will be reduced on light loadl and gradually increased as the load increases in proportion to the normal tendency of the disk to lag behind in its speed of rotation as the load increases.

A still urther obj ect of my invention is to provide a motor watt-meter for alternating currents which will be simple in construction, inexpensive in manufacture,l and eicient in'use. i

The embodiment `oi my invention herein disclosed, generally described, consists in a rotary dis r conducting the main current immersed ind loczlted ina magnetic-field the coils of which are in shunt across the lin'e,a' condenser in series with the coils of the field, a return pa'th above the disk for the Amagnetic lines preferably composed of laminated metal', and an inductive shunt around the' disk.

My invention will be more fully described hereinafter with reference to accompanying drawings in which the same is illustrated as embodied in a convenient and practical form and in which,- i

Figure 1 is principally diagrammatic, but in which parts are shown in vertical section; Fig. 2 a view showing the mercury cup and disk in plan and the coper-' ating 'parte diametrically; and Fig. 3 a vector diagram. l

Similar reference characters are used to designate similar parts'in the several figures of the drawing.

Reference letter A indicates a mercury cup formedl o any suitable insulating material. B designates a cover for the mercury cup, also made of insulating material, which is provided with a chamber b. C designates a cap for closing thetop of chamber b.

A disk G of' good conducting material, such as copper, isfimmersed in the mercury M in the cup A. g

'designates a vertical spindle extending concentrically through the disk G and to which the latter is aixed.

The lower end of the spindle g is tapered and rests upon l lating apparatus L.

` a conical bearing a, the latter being conveniently made in the form of a screw which is inserted in an opening through the bottom oi the mercury cup. he portion ofthe spindle which extends upwardly through the chamber b has fixed thereon a counterweight While the upper end of the spindle is tapered and engages a conical bearing d. the latter being preferably formed as a screw supported by a yoke l) mounted upon the cap C. A thinlble F depends from the cap C and concentrically surrounds the spindle y thereby preventing the escape from the chamber b oi any mercury which may flow thereinto from the mercury cup when the latter occupies any other position than a verA tical one.

E and E2 indicate the poles oi a magnet which extend through the bottom wall ol' the mercury cup A.

E designates the return path for the magneticl lines,

which is preferably formed of laminated metal and is supported within the cover B diametrically across the disk G.

l and l2 indicate conductor terminals which extend through the mercury cup in the same horizontal plane as the disk G and at diametrically opposite points.

L designates one line of the power circuit which is connectedto the terminal l while L2 designates a com tnuation of the line extending from the terminal l' and connecting with any suitable translating apparatus such as indicated at L. A

L3 indicates the return line extending from the translating apparatus L. The l'nes L and L:l are connected in any suitable manner either from a. dynamo or y from a transformer such as indica ted at T.

c indicates a shunt circuit leading from the line L) to the line L3 and comprising the energizing coils e and e2 which surround the cores E and El of the magnet. Located in sei-ies with the coils c and e and interposed between the same and the line L is a condenserli.V

40 A shunt circuit 'n which includes an inductive resistance extends from the line L tio line Lg. The inductive resistance indicated in Fig. l consists in a core N, the winding of which is in the shunt circuit n, and

a core n the energizing coil around which is connected in the main line L. The core N may preferably be formed of laminated metal and the poles thereof are spaced apart from the core n." so as to form small air gaps o and o2.

In Fig, 2 the inductive resistance in the shunt ci rcuit n is shown as consisting in a choke coil` the poles ofthe core N2 of which are loca-ted .adjacent to the ends of a yoke n?.

r indicates a non-inductive resistance in the main line between the shunt n and the terminal l to cause a portion of the current to pass through the shi'int around the disk G until the inductive resistance in the shunt increases suficiently to cause practically all ol' the current to pass through thedisk.

F designates a worm on the spindle g by means of ovvhich the rotary motion ol' the disk G is communicated to any suitable registering mechanism.

l The operation of my invention is as follnws: The alternating current passes from the dynamo or transformer T through the line Li-uun-inductive resistance r, terminal l, disk G, terminal l2. line L2, to the transbehind the increase in load.

is preferably such as indicated in Fig. 1 in which all o f y thence through the return line L3 to the dynamo or transformer. A portion of the current proportional to the'linc voltage also passes through the shunt circuitrc, windings c/ and eE of the magnetic field` condenser H to the return line L3. The reaction of the magnetic iield upon the disk G rotates the latter and the rotation thereof is recorded upon suitable registering apparatus operatively connected to the worm Fin any usual or well-known manner. -The condenser I-I impresses an electro-motive force on the coils a and e thereby bringing the magnetic field produced by them in phase with the line pressure on nonind ucti re load. lhe lagging oi the current in the coils e and c' due to their self-induction is thereby overcome so that the difference in phase between the impressed i. M. F. and the magnetic field is eliminated. By properly adjusting the self-induction and capacity of the. system any desired phase of the magnetism in the shunt field may be obtained and such adjustment may be conveniently accomplished by using f ied coils and a variable condenser, so that the meter may be readily adjusted to measure correctly either a noninductive or an inductive load to the lowest possible factor.

The condenser notonly impresses upon the shunt coils an E. M. F. in advance of the line pressure, but also increases the potential across the coilsof the magnetlic field. so that the-strength of the field ismuchY greater than that obtained by connecting them directly across the original line Without the employment of a condenser. It has been found :in practice that with a 100 volt 60 cycle circuit the condenser raises the pressure at least three or iour times.

The operation above described is graphica1ly'illus- I tinted in the vector diagram in Fig. 3, in which E ndicates the impressed line pressure; Cn the main current on non-inductive load; C the main current on inductive load; S the shunt current through the coils e and e2, lagging-8G degrees when the shunt is connected across the circuit; M the magnetic field of the shunt, the phase of which is that of the shunt current S; E the pressure impressed on the shunt coils c and e2 when the condenser is used, the phase' being 80 degrees in advance of and greater than that of the line pressure E; S2 the current in the shunt coilsdu'e'to E?, the i pressure impressed by the condenser; and M2 the magnetisrn which is in phase with the line pressure E owing to the pressure impressed on the coils by the condenser.

As previously stated, the rotation of the disk G does not increase proportionally as the' load increases. This error is partially eliminated by the employment of the' laminated metal return plate E3 for the magnetic lines owing to there being less eddy currents than when the return plate is made oi soft steel or cast iron. The re maining error is corrected by the inductive resistance located in shunt with the disk G which serves to shunt more oi the current when the load is light and-gradually in creases in reacta nce as the load increases thereby sending a greater proportion of thefcurrent through the disk and consequently increasing its speed of rotation. The reactive resistance through the inductive shunt should increase as the load increases in proportion to the norn'ial tendency of the speed of the disk to relatively fall The inductive resistance the load current passes through the primary energizing turns around the core n so that on light load the primary coil has very little effect on the inductive shunt through the lead n, but on full load the primary coil has a very great effect on the inductivepresistance in the shunt by introducing into the coil ol' the resistance a counter E. M. F. sufficient to cause practically in finite resistance through the shunt so that nearly all oi the current passes through the disk thereby resulting in maximum rotative torque at full load, whereas on light load the effect of the primary-winding is so slight upon the inductive shunt that only about one-half ol' the total current at that load passes through the disk G.

lt is obviously a simple matter to so adjust the rela tive primary and secondary coils inthe shunting device just described as to compensate for the normal tendency' of the disk to relatively fall behind in its speed of rota tion as the load increases. The non-inductive resist.- ance r serves to insure the passing ot a portion ol' the current across the shunt n on light load.

The presence of the air gaps o and o2 in the magnetic circuit of the shunting device is of importance inasmuch as in a closed magnetic circuit the effect of the shunting device ill not increase properly with the increasing load, as on very light load the maglieti sm Will be lower' in proportion for the magnetizing force than on hea'vier loads. This is due to the fact that the magnetism of soit iron initially increases very slowly with the magnetizing force and consequently by introducing an air gap in the magnetic circuit of the shunting device enough primary turns can be employed to initially magnetize the coil sufficiently for the lightest loads which the meterrmust measure, and the magnetization will then increase up to the highest load which the meter is adapted to measure.

In lieu of the inductive resistance above described, which is preferably employed, I may use an inductive resistance such as indicated in Fig. 2, consisting in a choke coil in the shunt n and the yoke n2 which owing tothe presence of the non-inductive resistance 1' carries approximately half of the current around the disk on light load', but as the load increases the reactance increases, thereby sending through the disk a greater proportion of the main current as the load increases.

From the foregoing description it will be observed that'I have invented an improved meter for alternating currents consisting of a mercury motor meter, such as heretofore used for direct currents, in connection with means fdr compensating for the lagging of the magnetic field due to the self-induction of' the 'shunt coils thereof, and in connection with compensating means for overcoming the tendency of the rotary conductor disk to fall behind in speed and not increase proportionally to the increase in load.

While I have described my invention as applied to a motor meter for alternating currents in which mercury is the conducting medium for electrically uniting the line toa rotary conductor7 yet it is to be understood that my invention may also' be applied to motor meters for alternating currents in which other conducting mediums or means than mercury may be employed for electrically connecting the rotary conductor to the line, and While I have described more or less precisely the details of construction, I do not wish to be understood as limiting myself' thereto, as I contemplate changes in form, in proportion of parts, and the substitution of equivalents as circumstances may suggest or render expedient, without departing from the spirit of my invention. l

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. ln n mercury motor watt meter for alternating currcnts. the combination with u rotary conductor through which thc main current passes to translating apparatus. of a body ot' mercury in which said conductor is immersed. :1 magnet in thc field of which said conductor is located, a coil lor energizingr said magnet located in shunt relativcl)`- to said conductor. and means for counteracting thc self-induction ot said coil und thereby bringing thc magnctic ficld in phase with the line pressure.

L. ln n mercury motor watt meter for alternating cul'- rcni's. f'he combination with arrotal'y conductor through which thc main current passes t0 translating apparatus. of u holly ot' mcrcury in which said conductor is immersed. :i magnet in thc field of which said conductor is located. :i coil for energizing said magnet located in a shunt across lhc liuc, and moans for imprcssing an electro-motive force ou .said coil so as to bring the magnetic field in phase with i'hc liuc pressure.

l. ln u mercury motor watt meter for alternating currcnts, The combination with a rotary conductor through which thc main current passes to translating apparatus. of a body of mercury in which said conductor is immersed, n magnet in the field of which said conductor is located. a coil for energizing said magnet located in a shunt across the linc. und a condenser in series with said coil.

4. ln a mercury motor watt meter for alternating cur rents. the combination with a rotary conductor through which the main current passes to translating apparatus. ol' n magnet inA the field of which said conductor is located. a cnil for energizing said magnet located in a shunt across the line, a body of mercury in which said conductor is immersed. and means for counter-acting the self-induction of said coil and so as to bring the magnetic field in4 phse -with the line pressure.

ln a mercury motor meter for alternating currents, the combination with a rotary conductor through which the main current passes to translating apparatus, of a body of mercury in which said conductor is immersed, a magnet in the field of which said conductor -s located, a coil for energizing said magnet, a condenser in series with said coil, both said coil and said condenser being located in a shunt across the line, and means operating as the load increases to increase the current passing through said conductor at a greater rate than the load increases.

6. 1n a mercury motor meter for alternating currents, the combination with alrotary conductor through which the main current passes to a translating device, of a body of mercury in which said conductor is immersed, a magnet in the field of which said conductor is located, a lcoil for energizing said magnet, a condenser in series with said coil. both said coil and condenser being located in a shunt across thehlne, and means for shunting around said rotary conductor a portion of the current, such portion gradually decreasing as the load increases.

7. In :i mercury motor meter for alternating current the combination with a 'rotary conductor through which the main current passes to a translating device of abody of mei-cur)` in which said conductor is immersed, a magnet iu thc field of which said conductor is located, a coil for energizing said magnet located in a shunt across the line, means for counter-acting the self-induction of said coil and thereby bringing the magnetic eld in phase with the line pressure, und un inductive shunt around said rotary conductor.

S. In a mercury motor meter for alternating currents. the combination with a rotary conductor through which the main current passes to a translating device, of a body of mercury in which said conductor is immersed, a magnet in the field of which said conductor is located, a coil for energizing said magnet located in a shunt across the line, moans for counteractlng the self-induction .of said coil an'd thereby bringing the magnetic field in phase with the lino und n transformer having its. secondary coil und its primary coil pressure, in shunt with said rotary conductor in thc main line.

9. in a mercury motor meter for ultcrnuting current, thc comhinution with a rotary conductor through which the main current passes to u translating device, of u body of mercury in which said conductor is immersed, u muguet in thu icld of which said conductor is locutcd, a coil for energizing s iti magnet located in a shunt across thc line, u condenser in serios with said coil :1nd means operating as thc load incrcas s tn incrcnsc thc currcnt missing through said conductor ut u :gi-cuter rate ot increase than that of the loud,

1i). In a mercury motor mctcr for alternating currcnts. thc combination with a rotury conductor through which the main current liasses lo u translating.,r device. of a hotly nf mercury in which Suid conductor is immersed, n. muguet in the icld uf which said disk is. located. a coil for cuorA magnet located in a shunt across the line, a and an inductive shunt gizing snif] condenser in s'erics with said coil, around Suid rotary conductor.

11. in a mercury motor meter for alternating currents, the combination with a rotary conductor through which the matin currcnt passes to translating,r apparatus, of a holly of mercury in which said conductor is immersed, a muguet in the icid of which said conductor is located, a coil for energizing said magnet located in a shunt across the line, and means operating as the load increases to incl-caso thc driving torque upon said conductor at a grcaicr rntc than the current increases.

1n testimony whereof, I sign this specification in the prcscncc uf two wines.

ROBERT C. LANPHIER.

Witnesses J. W, Aimnnus'rnn, )L F` O'lliunx. 

